Compliant heating system comprising a compressive seal expansion joint

ABSTRACT

A compliant heating system includes a dynamic component including a heat exchanger; a pressure vessel shell encompassing at least a portion of the heat exchanger; and a accessible and detachable compressive seal expansion that connects the dynamic component and the pressure vessel shell.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.15/217,243, filed Jul. 22, 2016, which claims priority to U.S.Provisional Patent Application Ser. No. 62/282,039 filed Jul. 24, 2015,the entire disclosure of each application above are incorporated hereinby reference to the extent permitted by applicable law.

BACKGROUND (1) Field

This application relates to a compliant heating system, methods ofmanufacture thereof, and method of using the compliant heating system.

(2) Description of the Related Art

Heating systems can fail due to mechanical stress, which develops fromdifferential thermal expansion of components of the heating systemduring heating or cooling of the system. The mechanical stress developsbecause components that undergo different amounts of thermal expansionare rigidly connected. The different amounts of thermal expansion canoccur because the components are heated to different temperatures, orbecause the components have different thermal expansion properties, forexample. For example, longitudinal thermal expansion of heatedcomponents, e.g., a furnace, combustor, and heat exchanger assembly,when rigidly attached in more than one location to other components,such as a pressure vessel shell can result in component failure. Theoccurrence of mechanical failure is particularly true of fluid heatingsystems for the production of hydronic (water), steam, and thermal fluidaimed at delivering hot liquid or steam for ambient temperatureregulation, hot water consumption, commercial applications, andindustrial process applications.

The mechanical stress induced by differential thermal expansion ispresent both in systems that incorporate tube-and shell heat exchangersand those that employ alternative heat exchanger designs, includingtubeless heat exchangers. Techniques for mitigating the mechanicalstress, such as complex floating head assemblies, curves and bends inthe heat exchanger tubes, and compliant bellows/corrugations, all havedrawbacks. For example, complex floating head assemblies located insidethe pressure vessel are not readily inspectable, serviceable, orreplaceable in the field and can have frequent maintenance; curves andbends in the heat exchanger tubes add compliance, but are not readilyinspectable, serviceable, or replaceable and can increase themanufacturing cost and material failure risk; and compliant bellows orcorrugations inside the pressure vessel are difficult to access, e.g.,for inspection or repair, resulting in poor system and component fieldserviceability.

Therefore there remains a need for an improved heating system that canreduce or eliminate mechanical stress that arises due to differentialthermal expansion.

SUMMARY

Disclosed herein is a compliant heating system including a compressiveseal expansion joint.

Also disclosed are methods of manufacturing the compliant heatingsystem.

Disclosed is a compliant heating system, including: a dynamic componentincluding a heat exchanger; a pressure vessel shell encompassing atleast a portion of the heat exchanger; and a compressive seal expansionjoint that connects the dynamic component and the pressure vessel shell.

Also disclosed is a compliant heating system including: a dynamiccomponent including a heat exchanger, an exhaust plenum that is disposedon an end of the heat exchanger, and an exhaust gas port; a pressurevessel shell encompassing at least a portion of the heat exchanger andincluding a pressure vessel shell conduit that is disposed along alateral axis and on an end of the pressure vessel shell, wherein theexhaust gas port laterally extends through the pressure vessel shellconduit; and an inner conduit compressive seal expansion joint and anouter conduit compressive seal expansion joint disposed on the pressureshell conduit, wherein the exhaust gas port is connected to the pressurevessel shell conduit via the inner conduit compressive seal expansionjoint and the outer conduit compressive seal expansion joint; whereinthe pressure vessel shell conduit includes a pressure vessel flange;wherein the pressure vessel flange is connected to a first end of a pipesegment via the inner conduit compressive seal expansion joint, whereina second end of the pipe segment is connected to a combustion gasexhaust port flange via the outer conduit compressive seal expansionjoint, and wherein the combustion gas exhaust port flange is rigidlyattached to the exhaust port via a connection flange.

Also disclosed is a method of manufacturing a compliant heating system,the method including: disposing a dynamic component including a heatexchanger in a pressure vessel shell; and connecting the dynamiccomponent and the pressure vessel shell with a compressive sealexpansion joint to manufacture the compliant heating system.

Also disclosed is a method of using the compliant heating system of anyone of the preceding claims, the method including: directing a thermaltransfer fluid through the heat exchanger to an exhaust gas port; andtransferring heat from the thermal transfer fluid to a production fluidlocated in an inner production fluid area

The above described and other features are exemplified by the followingfigures and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the figures, which are exemplary embodiments, and whereinthe like elements are numbered alike and wherein the dashed line inFIGS. 5A, 6A, and 7A denotes an axial axis:

FIG. 1A is a cross-section view of an embodiment of a heating systemwherein the exhaust flue is directed axially out of the base;

FIG. 1B is an expanded view of a portion of FIG. 1A showing attachmentpoints of the heating system;

FIG. 2A is a cross-section view of an embodiment of a heating systemwherein the exhaust flue is directed laterally out of the base;

FIG. 2B is an expanded view of a portion of FIG. 2A showing attachmentpoints of the heating system;

FIG. 3A is an illustration of an embodiment of a vertical standingheating system;

FIG. 3B is an illustration of an embodiment of a horizontal standingheating system;

FIG. 4A is a cross-section view of an embodiment of a compliant heatingsystem having a compliant pressure vessel conduit;

FIG. 4B is a cross-section view of a portion of FIG. 4A;

FIG. 4C is a perspective cut-away view of an embodiment of the compliantheating system of FIG. 4A;

FIG. 4D is a cross-section view of the compressive seal expansion jointof shown in FIG. 4A;

FIG. 5A is a cross-section view of an embodiment of a compliant heatingsystem including a U-tube exhaust flue, which is directed laterally outof the base;

FIG. 5B is a perspective cut-away view of a portion of the compliantheating system of FIG. 5A;

FIG. 5C is a cross-section view of the compressive seal expansion joint310 shown in FIG. 5A when differential thermal expansion is not present;

FIG. 5D is cross-section view of the compressive seal expansion joint310 shown in FIG. 5A when differential thermal expansion is present;

FIG. 6A is a cross-section view of an embodiment of a compliant heatingsystem wherein the exhaust flue is directed laterally out of the base;

FIG. 6B is a cross-section view of region b of FIG. 6A;

FIG. 6C is a cross-sectional section view of further illustrating thecompressive seal expansion joint shown in region c of FIG. 6B;

FIG. 6D is a perspective cut-away view of the compliant heating systemof FIG. 6A;

FIG. 6E is a cross-section view of the compliant heating system of FIG.6A when differential thermal expansion is not present;

FIG. 6F is a cross-section view of the compliant heating system of FIG.6A when differential thermal expansion is present;

FIG. 7A is a cross-section view of a portion of a compliant heatingsystem having a compliant pressure vessel shell;

FIG. 7B is perspective cut-away view of the compliant heating system ofFIG. 7A; and

FIG. 8 is a cross-section view of a compressive seal expansion joint.

DETAILED DESCRIPTION

Differential thermal expansion over repeated thermal cycling of aheating system can result in the mechanical failure in regions of highstress concentration. For example, mechanical failure can occur at rigidattachment locations between components that experience thermalexpansion and those that do not, or between components that experiencedifferent amounts of thermal expansion. The rigid attachment locationcan be, for example, between a dynamic component of the heating systemand the pressure vessel shell. While not wanting to be bound by theory,it is understood that mechanical failure can be initiated by localcracking failure mechanisms. Once the initial cracks are formed, exposedmetal within the cracks can undergo oxidation, leading to the formationof additional stresses at the crack tip, ultimately followed by crackpropagation and component failure.

Component failure in heating systems can be expensive and difficult torepair in the field. For example, disassembly of the pressure vessel toextract the heat exchanger or furnace elements is time consuming andlabor intensive, and reassembly often involves specialized welding orjoining techniques \. Furthermore, fluid heating systems thatincorporate methods for stress relief into the hot structures inside thepressure vessel (e.g., in the heat exchanger, in the combustion system,or in the furnace) are expensive and difficult to service, oftenprohibitively so, when the components of these stress relief devicesfail.

In order to overcome one or more of these drawbacks, disclosed is animproved compliant heating system. The compliant heating systemcomprises a compressive seal expansion joint that allows for thereduction or near elimination of stresses that would otherwise arise atattachment points between components that experience different amountsof thermal expansion. Due to the reduction of stress in the compliantheating system, failure of heat exchanger elements, such as heatexchanger tubes, can be reduced.

The compliant heating system can be designed to localize athermally-induced differential motion and mechanical stress specificallyto the compressive seal expansion joint. In the absence of thissystems-engineering approach to the design of the structure comprisingthe compressive seal expansion joint, the thermally-induced mechanicalstress can be otherwise distributed throughout the heating system,concentrating the failure risk to weaker elements or joints andrendering the likelihood of failure and the location of the failureunpredictable. While not wanting to be bound by theory, it is believedthat inclusion of the disclosed compressive seal expansion jointprotects the expensive, delicate, and hard-to-reach components frommechanical stress-induced failure.

The inventors have surprisingly discovered that the compressive sealexpansion joint can be located on the external pressure vessel shell oron an externally located conduit of the pressure vessel shell, where itis exposed and readily available for service. Since the compressive sealexpansion joint can function to localize the differential motion andmechanical stress to an external location, the expensive, delicate, andhard-to-reach components can be protected from mechanical stress-inducedfailure with the added benefit that it can be easily inspected andserviced. It is noted that the external location refers a locationexternal to the compliant heating system (such as one or both of theexternal pressure vessel shell or on an externally located conduit ofthe pressure vessel shell) and that the external location can beenclosed or at least partially enclosed, for example, with a removablecover or shield.

For example, the compressive seal expansion joint can be externallylocated on a pressure vessel shell or on an externally located conduitof the pressure vessel shell. An easily accessible compressive sealexpansion joint allows field servicing without the use of specializedequipment or complex joining techniques, such as welding. In thismanner, the compressive seal expansion joint can be regularly inspectedfor wear, cracking, or fatigue to enable problems to be addressed beforecomponent failure. This inspection can be performed periodically and caninvolve any suitable type of inspection, such as visual inspection, ornon-destructive inspection for detecting wear, cracking, and materialfatigue of the compressive seal expansion joint to anticipate andaddress problems before a failure occurs. A service life of thecompliant heating system can therefore be improved, and can be 10 to 30years or longer.

Moreover, the inventors have discovered that suitable thermal stressrelief can be provided using serviceable components in both the axialand lateral exhaust configurations. In either orientation, thermalstress relief can be incorporated in an external location in aninspectable, removable, replaceable, and serviceable manner. Thus theserviceable components of the production fluid pressure vessel of afluid heating system can be exposed for maintenance with little or nodisassembly of the compliant heating system.

When the thermally-induced mechanical stress is localized toreplaceable, compliant elements on the pressure vessel shell asdisclosed herein, the pressure limits of the production fluid pressurevessel and can satisfy current safety standards for fluid heating systempressure vessels.

A compliant heating system can comprise a shell and tube heat exchanger,where heat from a thermal transfer fluid located in a tube istransferred to a production fluid located in the pressure vessel shell.The thermal transfer fluid can be generated and/or heated in a furnace,and can be a product of combustion of a fuel. The heated thermaltransfer fluid can travel from the furnace through a tube to an exhaustplenum (also called an exhaust manifold), which is located at a distalend of the tube. The tube can comprise a plurality of heat exchangertubes. An upper tube sheet can be located between the furnace and thetube and a lower tube sheet can be located at an opposite distal end ofthe tube and between the tube and the exhaust plenum. The pressurevessel shell can be fixedly attached to one or more of the furnace, theupper tube sheet, the lower tube sheet, or the exhaust plenum. The heatexchanger (for example, a tube), and optionally one or both of thefurnace and the exhaust plenum, can be disposed within the pressurevessel shell.

The heat exchanger can exchange heat between the thermal transfer fluidand a production fluid, wherein the production fluid and the thermaltransfer fluid can each independently comprise one or both of a gas anda liquid. Thus, the compliant heating system can be used as agas-liquid, liquid-liquid, or gas-gas heating system. As used herein,the thermal transfer fluid is directed through the heat exchanger anddoes not contact the pressure vessel or the production fluid; and theproduction fluid is directed through the pressure vessel and is incontact with the inner surface of the pressure vessel shell and theouter surface of the heat exchanger.

The thermal transfer fluid can comprise a combustion gas, such as a gasproduced by fuel fired combustor. The thermal transfer fluid cancomprise one or more of water, steam, carbon monoxide, and carbondioxide. The production fluid can comprise one or more of an ester, adiester, a glycol, a silicone, water, steam, an oil (such as petroleumoil and mineral oil), and a chlorofluorocarbon (such as a halogenatedfluorocarbon, a halogenated chlorofluorocarbon, and a perfluorocarbon).A production fluid comprising glycol and water is specificallymentioned.

The compressive seal expansion joint can be located on one or both ofthe pressure vessel shell and a conduit of the pressure vessel shell.The conduit of the pressure vessel shell can be directed at an angle of0 to 180° from the pressure vessel shell relative to axial axis of thepressure vessel shell. The conduit of the pressure vessel shell can bedirected axially out of the base (for example, at an angle of 0°) or canbe directed in a lateral direction relative to the axial direction ofthe pressure vessel shell (for example, at an angle of 90°). The conduitof the pressure vessel shell can comprise a bend. The bend can have a 0to 180° bend relative to its axis of departure from the pressure vesselshell. For example, if the conduit is directed axially out of thepressure vessel shell, then the bend can have an angle of 0 to 180°relative to the axial axis, and if the conduit is directed laterally outof the pressure vessel shell, then the bend can have an angle of 0 to180° relative to the lateral axis. Any suitable bend can be used. A bendhaving an angle of 90° is mentioned.

FIG. 1A and FIG. 2A are cross-section views of an embodiment of aheating system in which the exhaust flue is directed axially out of thebase and is directed laterally out of the base, respectively. In thefigures, fan blower 100 forces air into combustion furnace 105 throughconduit 102. When a combustion furnace is present, the combustionfurnace can generate a thermal transfer fluid (e.g., hot air) andcombustion products, for example, by gas combustion, oil combustion,petroleum fuel combustion, electric energy conversion, or anycombination thereof. In the absence of a combustion furnace, hot gassescan be supplied by any suitable source, for example, exhaust from a hightemperature turbine, or high pressure boiler. The thermal transfer fluidtravels through heat exchanger section 138 extending from upper tubesheet 118 to lower tube sheet 122 via heat exchanger tubes 120 toexhaust plenum 126 and exits via exhaust gas port 132. The productionfluid enters the heating system via inlet port 134, traverses heatexchanger section 138, enters inner production fluid area 112, and exitsthrough outlet port 140. It is noted that upper tube sheet 118 and lowertube sheet 122 can be fixedly attached to pressure vessel shell 114, asillustrated in FIG. 1A and FIG. 2A, for example, to improve thestructural support of the heating system, or can have a width less thanthat of pressure vessel shell 114 such as is illustrated in FIG. 4B.When upper tube sheet 118 and lower tube sheet 122 are fixedly attachedto pressure vessel shell 114, upper tube sheet 118 and lower tube sheet122 can allow for the production fluid to pass through the respectivesheets. Conversely, one or both of upper tube sheet 118 and lower tubesheet 122 can prevent the through flow of the production fluid.

Pressure vessel shell 114 can be fixedly attached at one or moreattachment points, including, but not limited to furnace wall 108 (forexample, at furnace head attachment point 106), to a tube sheet (forexample at upper tube sheet attachment point 116 and at lower tube sheetattachment point 124), and to exhaust plenum wall 125 (for example, atbottom head attachment point 130). As shown in FIG. 1B, the pressurevessel shell 114 can comprise a pressure vessel shell top head 110,which is fixedly attached to furnace head 104 at furnace head attachmentpoint 106, and a pressure vessel shell bottom head 128, which is fixedlyattached at bottom head attachment point 130. As shown in FIG. 2B, thepressure vessel shell 114 can be fixedly attached to furnace head 104 atfurnace head attachment point 106 and pressure vessel shell 114 can befixedly attached to flange 129 at bottom head attachment point 130.

A body cover 136 can be removably attached to provide for easy access tothe heating system. Alternatively, or in addition, the body cover 136can comprise one or more removable panels to facilitate access forservice and maintenance. When the body cover 136 is removed or opened,one or more of the exterior components of the heating system can beaccessed. Examples of exterior components can include, but are notlimited to, furnace head 104, pressure vessel shell 114, exhaust plenumwall 125, and exhaust gas port 132. Also, because the pressure vesselshell is fixedly attached in proximity to the heat exchanger section,for example, by welding, the interior components, such as the heatexchanger tube and the furnace, are inaccessible.

FIG. 3A and FIG. 3B are illustrations of embodiments of a verticalstanding heating system and of a horizontal standing heating system,respectively. As shown in FIG. 3A and FIG. 3B, exterior components areaccessible when the body cover is removed. Specifically, FIG. 3A andFIG. 3B illustrate that accessible exterior components can comprise tophead assembly 200, pressure vessel shell 114, base 210, exhaust flue206, inlet port 134, and outlet port 140.

When the compliant heating system is quiescent, the furnace and heatexchanger assembly may be at room temperature, e.g., 23 to 25° C. Inoperation, the temperature of the furnace and heat exchanger areincreased and the components expand. The expansion can occur in an axialdirection, e.g., in a longitudinal direction along a major axis, forexample, along a central axis of the compliant heating system. Thecomponents along the path of the thermal transfer fluid, such as thefurnace, the upper tube sheet, the heat exchanger tube, the lower tubesheet, and the exhaust plenum can be subjected to high temperaturesduring the operation of the compliant heating system and can thereforeundergo thermal expansion which is greater than a thermal expansion ofthe pressure vessel shell, which is in contact with the production fluidand thus remains at a lower temperature and thus can undergo little tono thermal expansion during operation. Along the axial direction of thefluid heating system, the expansion of the individual metal componentscan be additive.

For example, the inventors have modelled exemplary boilers having athermal input of only less than 880 kilowatts (kW) can experience morethan 0.5 mm of unconstrained differential thermal expansion. Inconstrained systems, this low level of thermal expansion could result inpeak stresses of greater than or equal to 150 megapascal (MPa).Conversely, the presently disclosed compliant heating systems that allowfor the expansion of the dynamic component, the peak stresses under thesame conditions can be reduced, for example, to only about 40 MPa, whichcould exist almost completely in the radial direction. This reduction instress within the system can correspond to an increased lifetime of thecomponents therein.

As is described herein, a compressive seal expansion joint can be usedto alleviate or eliminate stresses that arise due to the differentialthermal expansion that occurs during operation of the compliant heatingsystem. The compressive seal expansion joint can comprise a gasket 326,which covers an expansion gap, and a retaining ring 320, which isdisposed around the gasket. The gasket can function to seal theexpansion gap and prevent an internal fluid, e.g., the production fluid,from leaking out of the compressive seal expansion joint and can alsofunction to provide a flexible element that can form an articulatedhinge with one or more degrees of freedom of movement. An embodiment inwhich the gasket provides three degrees of freedom of movement ismentioned. One or both of a width and an angle of the expansion gap canincrease and decrease depending on the differential thermal expansion ofthe compliant heating system. The width of the gap when the system is atroom temperature, e.g., 23 to 25° C., can be greater than 0 to 5millimeters (mm), or 1 to 5 mm, or 1 to 4 mm.

The gasket can comprise any suitable material, such as an elastomer. Thegasket can comprise one or more of a styrene based elastomer (such asstyrene-butadiene-styrene (SBS) block copolymer, astyrene-ethylene-butadiene-styrene (SEBS) block copolymer, astyrene-(styrene butadiene)-styrene block copolymer, a styrene butadienerubber (SBR), an acrylonitrile-butadiene-styrene copolymer (ABS)), abutadiene rubber (BR), a natural rubber (NR), an isoprene rubber (IR),an ethylene-propylene-diene monomer (EPDM) (for example, a partial orcomplete hydride thereof), a fluoroelastomer (such those derived fromone or more of vinylidene fluoride, hexafluoropropylene,pentafluoropropylene, tetrafluoroethylene, and chlorotrifluoroethylene),and a nitrile material.

The retaining ring can provide an internal channel to house the gasket.The retaining ring can be a flexible retaining ring or can be a rigidretaining ring, and can comprise a hinge to allow for the retaining ringto be easily added or removed. The retaining ring can be secured to thecompliant heating system by a fixing means. Examples of fixing meansinclude a threaded bolt (such as that illustrated in FIG. 4C), a clasp,a lock, a snap, or a draw latch.

One or more positioners can be used to guide the retaining ring tomaintain a lateral position on the pressure vessel shell. The positionercan comprise one or both of a protrusion, such as ridge 352, and acorresponding depression, such as slot 350. The depression or theprotrusion of the positioner can be located on the pressure vessel shellor on a pressure vessel shell conduit. In an embodiment, one of theretaining ring and the pressure vessel shell includes a protrusion, suchas a ridge or stud that can fit into a corresponding depression, such asa slot or a well, which is disposed in the other of the retaining ringand the pressure vessel shell. For example, FIG. 8 illustrates thatretaining ring 320 can comprise a ridge 352 that correspond to slot 350.

The compressive seal expansion joint can be located on an exteriorcomponent of the compliant heating system. The compressive sealexpansion joint can be located on the pressure vessel shell, e.g., on anexterior surface of the pressure vessel shell. The pressure vessel shellcan comprise a pressure vessel shell conduit which extends from an endor from a side of the pressure vessel shell, and the compressive sealexpansion joint can be located on the pressure vessel shell conduit,e.g., on an exterior surface of the pressure vessel shell conduit. Thepressure vessel shell and the dynamic components, such as the furnace,the upper tube sheet, the lower tube sheet, and the exhaust plenum, canbe attached via the compressive seal expansion joint and a rigidattachment point, for example, a single rigid attachment point, allowingfor the differential thermal expansion of the dynamic components and thepressure vessel shell with reduced mechanical stress.

The compressive seal expansion joint can accommodate a total axialdeflection of the dynamic components of 0.01 to 15 millimeters (mm), or0.1 to 8 mm, or 0.1 to 5 mm, or 0.01 to 5 mm.

The compressive seal expansion joint can contain a pressurizedproduction fluid in the pressure vessel shell. In an embodiment, thecompressive seal expansion joint can contain a production fluid having apressure of 50 to 1,750 kilopascals (kPa), 100 to 1,400 kPa, or 200 to1,200 kPa.

The compressive seal expansion joint can have a fatigue life of 150,000to 1,000,000 cycles, where 1 cycle is equal to one heating and coolingcycle of the compliant heating system.

It has been further unexpectedly discovered that use of a plurality ofcompressive seal expansion joints results in synergistic effectsresulting in further improved performance. While not wanting to be boundby theory, it is believed that use of a plurality of compressive sealexpansion joints provides for an improved ability to accommodate complexstress, such as stress which develops from angular displacement,resulting in torque, as is further disclosed in conjunction with FIG. 6Eand FIG. 6F below. The compliant heating system may comprise 2 to 10, 3to 8, or 4 to 6 compressive seal expansion joints. An embodiment inwhich the compliant heating system comprises 2 compressive sealexpansion joints is mentioned.

FIGS. 4A to 4D illustrate an embodiment of a compliant heating systemhaving a compressive seal expansion joint located on a pressure vesselshell conduit of the pressure vessel shell. As shown in FIG. 4A, thethermal transfer fluid travels from combustion furnace 105 through heatexchanger tubes 120 to exhaust plenum 126 and exits via exhaust gas port132 that is directed axially out of the base. A base of the exhaustplenum can be pitched towards exhaust gas port 132 to facilitate removalof a condensate in condensing applications. Pressure vessel shell 114can comprise pressure vessel flange 330 that laterally extends out ofpressure vessel shell 114 and that can be located around a portion ofexhaust gas port 132, for example, as illustrated in FIG. 4B and FIG.4C. Pressure vessel flange 330 is connected to combustion gas exhaustport flange 332 via outer compressive seal expansion joint 310.Combustion gas exhaust port flange 332 can be rigidly connected toexhaust gas port 132 via connection flange 334, for example, via welds340. Compressive seal expansion joint 310 comprises retaining ring 320located around gasket 326, where gasket 326 is located over expansiongap 324, for example, as illustrated in FIG. 4D. Retaining ring 320 canbe secured via threaded bolt 322, as illustrated in FIG. 4C. Thepressure vessel flange 330 and the exhaust port flange 332 can definethe expansion gap therebetween.

FIGS. 5A to 5D show a cross-section view of another embodiment of thecompliant heating system in which a U-tube exhaust flue is directedlaterally out of the base. Due to the lateral directionality of theexhaust flue, the overall length of the compliant heating system can bereduced and can allow for a facilitated ducting of the exhaust gas. InFIG. 5A, the thermal transfer fluid travels from combustion furnace 105through heat exchanger tubes 120 to exhaust plenum 126 and exits viaexhaust gas port 132 that comprises the U-tube directed laterally out ofthe base. The pressure vessel shell 114 can comprise a curved pressurevessel shell conduit 402 that laterally extends out of pressure vesselshell 114 and that can be located around a portion of exhaust gas port132, for example, as illustrated in FIG. SA and FIG. 5B. Curved pressurevessel shell conduit 402 can be connected to combustion gas exhaust portflange 332 via compressive seal expansion joint 310. Curved pressurevessel shell conduit 402 can optionally comprise pressure vesselextension 412, for example, as is illustrated in FIG. 5C. Combustion gasexhaust port flange 332 can be rigidly connected to exhaust gas port 132via connection flange 334, for example, via welds 340. Also, as shown inFIG. 5A, an axis of the compressive seal expansion joint 310 can beparallel to the axial direction of the of the pressure vessel.

FIG. 5C and FIG. 5D illustrate how a compressive seal expansion jointcan accommodate the differential thermal expansion of the heatingsystem. FIG. 5C illustrates a cooled state of the compliant heatingsystem and FIG. 5D illustrates a heated state of the compliant heatingsystem undergoing axial expansion 360. Axial expansion 360 of thedynamic components when heated can result in an increase in the gapwidth from initial cooled gap width 324-c to heated gap width 324-h ofcompressive seal expansion joint 310.

The compressive seal expansion joint illustrated in FIGS. 4A to 4D canfunction similarly to that illustrated in FIGS. 5A to 5D.

FIGS. 6A to 6F illustrate an embodiment of a compliant heating systemhaving two compressive seal expansion joints located on a conduit of thepressure vessel shell. In FIGS. 6A to 6F, the exhaust flue is directedlaterally out of the base and two compressive seal expansion joints aredisposed thereon. In the configuration of FIG. 6A, the thermal transferfluid travels from combustion furnace 105 through heat exchanger tubes120 to exhaust plenum 126 and exits via exhaust gas port 132 that isdirected laterally out of the base. Pressure vessel shell 114 cancomprise pressure vessel flange 330 that laterally extends out ofpressure vessel shell 114 and that can be located around a portion ofexhaust gas port 132, for example, as illustrated in FIG. 6B and FIG.6C. Pressure vessel flange 330 can be connected to a first end of pipesegment 314 via inner compressive seal expansion joint 310-a and asecond end of pipe segment 314 can be connected to combustion gasexhaust port flange 332 via outer compressive seal expansion joint310-b. Combustion gas exhaust port flange 332 can be rigidly connectedto exhaust gas port 132 via connection flange 334, for example, viawelds 340. Each of inner compressive seal expansion joint 310-a andouter compressive seal expansion joint 310-b comprise retaining ring 320located around gasket 326, where gasket 326 is located over expansiongap 324, for example, as illustrated in FIG. 6C. Retaining ring 320 canbe secured via threaded bolt 322, as illustrated in FIG. 6D.

FIG. 6E and FIG. 6F illustrate an embodiment of how multiple compressiveseal expansion joints can accommodate the differential thermal expansionof the heating system, where inner compressive seal expansion joint310-a and outer compressive seal expansion joint 310-b eachindependently form an articulated hinge with three degrees of freedomallowing for both axial expansion and angular displacement. FIG. 6Eillustrates a cooled state of the compliant heating system and FIG. 6Fillustrates a heated state of the compliant heating system undergoingaxial expansion 360. Axial expansion 360 of the dynamic components whenheated can result in a decrease in the gap width in one or both of innercompressive seal expansion joint 310-a and outer compressive sealexpansion joint 310-b. Likewise, axial expansion 360 can result in anangular displacement. The angular displacement can be defined by anangle α or γ as measured from a line perpendicular to an initial line,m, defined by combustion gas exhaust port flange 332. α and γ can eachindependently be 0.1° to 45°, or 0.1 to 25°, or 0.5° to 10°, or 0.1 to5°. Use of more than one compressive seal expansion joint can allow forthe axial expansion of the dynamic components without inducing a torqueon the rigid structures. Use of more than one compressive seal expansionjoint can result in a reduced activation force to deform the compressiveseal expansion joint during the axial expansion of the dynamiccomponents.

In comparing the compliant heating systems of FIGS. 4A to 4D, FIGS. 5Ato 5D, and FIGS. 6A to 6F it is observed that the exhaust gas port ofthe compliant heating system of FIGS. 4A to 4D is directed axially awayfrom the compliant heating system, whereas the exhaust gas port of thecompliant heating system of FIGS. 5A to 5D, and FIGS. 6A to 6F aredirected laterally away from the compliant heating system. In thecompliant heating system of FIGS. 4A to 4D, where the exhaust gas portis directed axially away from the compliant heating system, thedifferential thermal expansion of the dynamic component acts along theaxial axis (as denoted by the dashed line in FIG. 4A) of the fluidheating system and is aligned with the applied strain on the compressiveseal expansion joint. Likewise, although the exhaust gas port of thecompliant heating system of FIGS. 5A to 5D is directed laterally awayfrom the compliant heating system, the presence of the U-tube allows forthe resultant strain on the compressive seal expansion joint that arisesfrom the thermal expansion of the dynamic component to be in the sameaxial direction (i.e., that is parallel to the axial axis). The strainresponse of the compressive seal expansion joints when the resultantstrain is in the lateral direction can be dependent upon the compressiveand expansive properties of the gasket material and can result in alinear or non-linear response. In contrast, when the exhaust gas port isdirected laterally away (for example, in a direction perpendicular tothe axial axis) such that the resultant strain on the compressive sealexpansion joint is not in the axial direction, then the lateralredirection of exhaust gases can alter the stress patterns at thedownstream end of the hot assembly and can introduce new lateral andradial stress components. The presence of more than one compressive sealexpansion joint in the compliant heating system helps to alleviate thesenew stress components.

In this configuration, the sliding friction forces associated withmovement can be negligible or may be eliminated entirely. However, incertain embodiments an internal pressure based force may be present thatacts to “straighten” the section of pipe, and relates to the lengthbetween the expansion joints, the diameter of the expansion joints andthe diameter of the expansion joint. Specifically mentioned is a casewhere the return force from internal pressure is 1000 to 20,000 poundsforce, 2000 to 10,000 pounds force, or 3000 and 7000 pounds force.

FIGS. 7A to 7B illustrate an example of a compliant heating systemhaving a compressive seal expansion joint located on the pressure vesselshell. In the embodiment of FIG. 7A, the thermal transfer fluid travelsfrom combustion furnace 105 through heat exchanger tubes 120 to exhaustplenum 126 and exits via exhaust gas port 132. FIG. 7A illustrates thatpressure vessel shell 114 can be connected to compliant pressure vesselflange 512 via compressive seal expansion joint 310. Compliant pressurevessel flange 512 can be rigidly connected to top head flange 510, forexample, via a weld or compliant pressure vessel flange 512 and top headflange 510 can be a single piece. Compressive seal expansion joint 310comprises retaining ring 320 located around a gasket, where the gasketis located over expansion gap 324. Retaining ring 320 can be secured viathreaded bolt 322, as illustrated in FIG. 7B. It is noted that whilecompressive seal expansion joint 310 is located proximal to top headflange 510, the reverse configuration is also applicable, where the tophead of the pressure vessel shell is rigidly attached and where acompressive seal expansion joint is located on the distal end of thepressure vessel shell.

Also disclosed is a compliant heating system comprising a compressiveseal expansion joint located on the pressure vessel shell conduit of thepressure vessel shell, e.g., as shown in FIG. 6A, and compressive sealexpansion joint located on the pressure vessel shell, e.g., as shown inFIGS. 7A and 7B. While not wanting to be bound by theory, it is believedthat by providing redundant accommodation of thermal stress, improvedreliability may be provided. The compressive seal expansion jointlocated on the pressure vessel shell conduit and the compressive sealexpansion joint located on the pressure vessel shell are as previouslydisclosed, and thus repetitive description is omitted for clarity.

It is observed that in all of the embodiments of FIGS. 4-7 that thecompressive seal expansion joint(s) are externally located on either thepressure vessel shell or on an externally located conduit of thepressure vessel shell. As is noted above, the external location of thecompressive seal expansion joint allows for field servicing without theuse of specialized equipment or complex joining techniques such aswelding. This facilitated field servicing can allow for regularinspection of the compressive seal expansion joint for wear, cracking,or fatigue to enable problems to be addressed before component failure.Because the compressive seal expansion joint can be easily inspected,damaged compressive seal expansion joints can be easily replaced priorto failure, resulting in a longer lifetime of the compliant heatingsystem as compared to non-compliant heating systems.

The various components of the compliant heating system can eachindependently comprise any suitable material. Use of a metal isspecifically mentioned. Representative metals include iron, aluminum,magnesium, titanium, nickel, cobalt, zinc, silver, copper, and an alloycomprising at least one of the foregoing. Representative metals includecarbon steel, mild steel, cast iron, wrought iron, a stainless steelsuch as a 300 series stainless steel or a 400 series stainless steel,e.g., 304, 316, or 439 stainless steel, Monel, Inconel, bronze, andbrass. Specifically mentioned is an embodiment in which the heatexchanger core and the pressure vessel each comprise steel, specificallystainless steel. The compliant heating system may comprise a furnace, anupper tube sheet, a lower tube sheet, and an exhaust plenum, and thefurnace, the upper tube sheet, the lower tube sheet, and the exhaustplenum can each independently comprise any suitable material. Use of asteel, such as mild steel or stainless steel this mentioned. While notwanting to be bound by theory, it is understood that use of stainlesssteel in the dynamic components can help to keep the components belowtheir respective fatigue limits, potentially eliminating fatigue failureas a failure mechanism.

The disclosed compliant heating system can provide one for more of thefollowing benefits. First, mechanical stress that arises due to thedifferential thermal expansion of some of the components can belocalized to one or more specific locations of the compressive sealexpansion joint. Second, the compressive seal expansion joint can belocated on an external component of the compliant heating system, suchas a pressure vessel shell or on a conduit allowing for easy access forinspection and/or service. Third, in the disclosed configuration, thecompressive seal expansion joint can be inspected and/or servicedwithout welding or specialized techniques or tooling.

An example of a compliant heating system is a boiler, for example, forthe production of hot thermal fluids (such as steam, hot water,non-water based fluids, or a combination comprising one or more of theforegoing). The hot thermal fluids can be used for ambient temperatureregulation or water heating. The compliant heating system can be usedfor domestic, commercial, or industrial applications. In the compliantheating system, the thermally-induced mechanical stress can be localizedto replaceable, compliant elements on the exterior pressure vessel toprovide improved reliability.

The disclosed system can alternately comprise, consist of, or consistessentially of, any appropriate components herein disclosed. Thedisclosed system can additionally be substantially free of anycomponents or materials used in the prior art that are not necessary tothe achievement of the function and/or objectives of the presentdisclosure.

The terms “a” and “an” do not denote a limitation of quantity, butrather denote the presence of at least one of the referenced item. Theterm “or” means “and/or” unless clearly indicated otherwise by context.Reference throughout the specification to “an embodiment”, “anotherembodiment”, “some embodiments”, and so forth, means that a particularelement (e.g., feature, structure, step, or characteristic) described inconnection with the embodiment is included in at least one embodimentdescribed herein, and may or may not be present in other embodiments. Inaddition, it is to be understood that the described elements may becombined in any suitable manner in the various embodiments. “Optional”or “optionally” means that the subsequently described event orcircumstance may or may not occur, and that the description includesinstances where the event occurs and instances where it does not. Theterms “first,” “second,” and the like, “primary,” “secondary,” and thelike, as used herein do not denote any order, quantity, or importance,but rather are used to distinguish one element from another. The terms“front”, “back”, “bottom”, and/or “top” are used herein, unlessotherwise noted, merely for convenience of description, and are notlimited to any one position or spatial orientation.

The endpoints of all ranges directed to the same component or propertyare inclusive of the endpoints, are independently combinable, andinclude all intermediate points. For example, ranges of “up to 25 N/m,or more specifically 5 to 20 N/m” are inclusive of the endpoints and allintermediate values of the ranges of “5 to 25 N/m,” such as 10 to 23N/m.

Unless defined otherwise, technical and scientific terms used hereinhave the same meaning as is commonly understood by one of skill in theart to which this invention belongs.

All cited patents, patent applications, and other references areincorporated herein by reference in their entirety. However, if a termin the present application contradicts or conflicts with a term in theincorporated reference, the term from the present application takesprecedence over the conflicting term from the incorporated reference.

Disclosed is a compliant heating system, comprising: a dynamic componentcomprising a heat exchanger; a pressure vessel shell encompassing atleast a portion of the heat exchanger; and a compressive seal expansionjoint that connects/joins/is located between the dynamic component andthe pressure vessel shell.

Also disclosed is a compliant heating system comprising: a dynamiccomponent comprising a heat exchanger, an exhaust plenum that isdisposed on an end of the heat exchanger, and an exhaust gas port; apressure vessel shell encompassing at least a portion of the heatexchanger and comprising a pressure vessel shell conduit that isdisposed along a lateral axis and on an end of the pressure vesselshell, wherein the exhaust gas port laterally extends through thepressure vessel shell conduit; and an inner conduit compressive sealexpansion joint and an outer conduit compressive seal expansion jointdisposed on the pressure shell conduit, wherein the exhaust gas port isconnected to the pressure vessel shell conduit via the inner conduitcompressive seal expansion joint and the outer conduit compressive sealexpansion joint; wherein the pressure vessel shell conduit comprises apressure vessel flange; wherein the pressure vessel flange is connectedto a first end of a pipe segment via the inner conduit compressive sealexpansion joint, wherein a second end of the pipe segment is connectedto a combustion gas exhaust port flange via the outer conduitcompressive seal expansion joint, and wherein the combustion gas exhaustport flange is rigidly attached to the exhaust port via a connectionflange.

Also disclosed is a method of manufacturing a compliant heating system,the method comprising: disposing a dynamic component comprising a heatexchanger in a pressure vessel shell; and connecting the dynamiccomponent and the pressure vessel shell with a compressive sealexpansion joint to manufacture the compliant heating system.

Also disclosed is a method of using the compliant heating system of anyone of the preceding claims, the method comprising: directing a thermaltransfer fluid through the heat exchanger to an exhaust gas port; andtransferring heat from the thermal transfer fluid to a production fluidlocated in an inner production fluid area.

In any of the foregoing of embodiments, a thermal expansion of thedynamic component and a thermal expansion of the pressure vessel whenthe heat exchanger exchanges heat may be different; and/or the pressurevessel shell may further comprise a pressure vessel shell conduit, andthe compressive seal expansion joint may comprises a conduit compressiveseal expansion joint disposed on the pressure vessel shell conduit;and/or the pressure vessel shell conduit maybe disposed along an axialaxis and on an end of the pressure vessel shell, wherein the dynamiccomponent may further comprise an exhaust plenum, which is disposed onan end of the heat exchanger, wherein the exhaust plenum is connected toan exhaust gas port that axially extends through the pressure vesselshell conduit, and wherein the exhaust gas port is connected to thepressure vessel shell conduit via the conduit compressive seal expansionjoint; and/or the pressure vessel shell conduit may comprise a pressurevessel flange, wherein the pressure vessel flange is connected to acombustion gas exhaust port flange via the conduit compressive sealexpansion joint, and wherein the combustion gas exhaust port flange isrigidly attached to an exhaust port via a connection flange; and/or thepressure vessel shell conduit maybe disposed along a lateral axis and onan end of the pressure vessel shell, wherein the dynamic componentfurther comprises an exhaust plenum, which is disposed on an end of theheat exchanger, and an exhaust gas port that laterally extends throughthe pressure vessel shell conduit, and wherein the exhaust gas port isconnected to the pressure vessel shell conduit via the conduitcompressive seal expansion joint; and/or the pressure vessel shellconduit may have a bend of 0 to 180° relative to a lateral axis of thepressure vessel shell; and/or the pressure vessel shell conduit may havea 90° bend that connects the exhaust plenum and the exhaust gas port,and wherein the bend is in a direction towards in the axial direction ofthe pressure vessel, wherein an axis of the conduit compressive sealexpansion joint is parallel to the axial direction of the of thepressure vessel; and/or the pressure vessel shell conduit may comprise acurved pressure vessel shell conduit, wherein a combustion gas exhaustport flange is connected to the conduit compressive seal expansion jointopposite the curved pressure vessel shell conduit, and wherein thecombustion gas exhaust port flange is rigidly attached to the exhaustport via a connection flange; and/or the conduit compressive sealexpansion joint maybe located on the lateral axis; and/or the pressurevessel shell conduit may comprise a pressure vessel flange, wherein thepressure vessel flange is connected to a first end of a pipe segment viaan inner conduit compressive seal expansion joint, wherein a second endof the pipe segment is connected to a combustion gas exhaust port flangevia an outer conduit compressive seal expansion joint, and wherein thecombustion gas exhaust port flange is rigidly attached to the exhaustport via a connection flange; and/or the compressive seal expansionjoint may comprise a shell compressive seal expansion joint located on aside of the pressure vessel shell; and/or the pressure vessel shell maycomprise a lower tube sheet which is rigidly connected the heatexchanger, wherein the heat exchanger is in fluid communication with anexhaust plenum through the lower tube sheet, and wherein the shellcompressive seal expansion joint is located at an end of the pressurevessel shell which is distal to the exhaust plenum; and/or the dynamiccomponent may further comprise an exhaust plenum, wherein the exhaustplenum is connected to an exhaust gas port that extends through thepressure vessel shell; and/or the shell compressive seal expansion jointmay be located at an end of the pressure vessel shell which is proximalto an exhaust plenum; and/or the pressure vessel shell may be connectedto a compliant pressure vessel flange via the shell compressive sealexpansion joint, and wherein the compliant pressure vessel flange isrigidly attached to a top head flange; and/or the compressive sealexpansion joint may be removable; and/or the compressive seal expansionjoint may comprise a retaining ring comprising an internal channel,wherein a gasket is located in the internal channel; and/or thecompressive seal expansion joint may be configured to accommodate achange in a gap width of an expansion gap; and/or the compressive sealexpansion joint may be configured to accommodate a change in an angle ofan expansion gap; and/or the compressive seal expansion joint maycomprise a retaining ring comprising a positioner; and/or thecompressive seal expansion joint may be displaced upon heating of thecompliant heating system in response to a combined sliding frictionactivation force and pressure induced return force between 1,000 poundsforce and 12,000 pounds force; and/or the compliant heating system maycomprise two or more compressive seal expansion joints; and/or thedynamic component may further comprise a combustion furnace; and/or thecombustion furnace may be disposed in the pressure vessel shell; and/orthe dynamic component may further comprise an exhaust plenum; and/or theheat exchanger may comprise a plurality of heat exchanger tubes.

At least what is claimed is:
 1. A compliant heating system, comprising:a dynamic component comprising a heat exchanger having a plurality oftubes fluidically connected to an exhaust plenum that is fluidicallyconnected to an exhaust port along which flows exhaust from the heatexchanger; a pressure vessel encompassing at least a portion of the heatexchanger wherein the exhaust port sealingly penetrates the pressurevessel to provide the exhaust outside of the pressure vessel; at leastone shell expansion joint that detachably connects the dynamic componentand the pressure vessel, the expansion joint configured to reducethermally-induced stress on the dynamic component in operation; andwherein the pressure vessel comprises a pressure vessel conduit, theexhaust port is sealingly attached to the pressure vessel conduit, andthe at least one shell expansion joint is directly externally accessibleand detachably disposed on an exterior surface of the pressure vesseland detachable from outside of the heating system.
 2. The compliantheating system of claim 1, wherein the pressure vessel comprises a lowertube sheet which is rigidly connected to the heat exchanger, wherein theheat exchanger is in fluid communication with the exhaust plenum throughthe lower tube sheet, and wherein the shell expansion joint is locatedat an end of the pressure vessel shell which is distal to the exhaustplenum.
 3. The compliant heating system of claim 1, wherein the shellexpansion joint is located at an end of the pressure vessel, which isproximal to the exhaust plenum or distal to the exhaust plenum.
 4. Thecompliant heating system of claim 1, wherein the pressure vessel isconnected to a compliant pressure vessel flange via the shell expansionjoint, and wherein the compliant pressure vessel flange is rigidlyattached to a top head flange.
 5. The system of claim 1, wherein the atleast one shell expansion joint comprises: a removable gasket disposedacross a respective expansion gap; and a removable retaining ringdisposed around the gasket, which secures the gasket in place.
 6. Thesystem of claim 5, wherein the gasket comprises an elastomer.
 7. Thesystem of claim 5, wherein the retaining ring comprises an internalchannel arranged to house the gasket.
 8. The system of claim 5, furthercomprising one or more positioners arranged to guide the retaining ringto maintain position on the pressure vessel.